Problem 40 - Chemistry: The Central Science

Question

Write the balanced molecular and net ionic equations for each of the following neutralization reactions: (a) Aqueous acetic acid is neutralized by aqueous barium hydroxide. (b) Solid chromium(III) hydroxide reacts with nitrous acid. (c) Aqueous nitric acid and aqueous ammonia react.

Step-by-Step Solution

Answer

(a) Balanced molecular equation: \(HC_{2}H_{3}O_{2}(aq) + Ba(OH)_{2}(aq) \rightarrow H_{2}O(l) + Ba(C_{2}H_{3}O_{2})_{2}(aq) \) Balanced net ionic equation: \(H^{+}(aq) + OH^{-}(aq) \rightarrow H_{2}O(l)\) (b) Balanced molecular equation: \(Cr(OH)_{3}(s) + 3HNO_{2}(aq) \rightarrow 3H_{2}O(l) + Cr(NO_{2})_{3}(aq) \) Balanced net ionic equation: \(Cr(OH)_{3}(s) + 3H^{+}(aq) \rightarrow 3H_{2}O(l) + Cr^{3+}(aq)\) (c) Balanced molecular equation: \(HNO_{3}(aq) + NH_{3}(aq) \rightarrow H_{2}O(l) + NH_{4}NO_{3}(aq) \) Balanced net ionic equation: \(H^{+}(aq) + NH_{3}(aq) \rightarrow H_{2}O(l) + NH_{4}^{+}(aq)\)

Step 1: Identify reactants and predict products

The reactants are aqueous acetic acid (HC₂H₃O₂) and aqueous barium hydroxide (Ba(OH)₂). Since it's a neutralization reaction, the products will be water (H₂O) and a salt, in this case, barium acetate (Ba(C₂H₃O₂)₂).

Step 2: Write the balanced molecular equation

Balance the equation by making sure the number of atoms of each element is equal on both sides: \(HC_{2}H_{3}O_{2}(aq) + Ba(OH)_{2}(aq) \rightarrow H_{2}O(l) + Ba(C_{2}H_{3}O_{2})_{2}(aq) \)

Step 3: Write the balanced net ionic equation

Remove the spectator ions in the balanced molecular equation to get the balanced net ionic equation: \(H^{+}(aq) + C_{2}H_{3}O_{2}^{-}(aq) + OH^{-}(aq) \rightarrow H_{2}O(l) + C_{2}H_{3}O_{2}^{-}(aq)\) (b):

Step 1: Identify reactants and predict products

The reactants are solid chromium(III) hydroxide (Cr(OH)₃) and nitrous acid (HNO₂). The products will be water (H₂O) and a salt, which is chromium(III) nitrite (Cr(NO₂)₃).

Step 2: Write the balanced molecular equation

Balance the equation by making sure the number of atoms of each element is equal on both sides: \(Cr(OH)_{3}(s) + 3HNO_{2}(aq) \rightarrow 3H_{2}O(l) + Cr(NO_{2})_{3}(aq) \)

Step 3: Write the balanced net ionic equation

Remove the spectator ions in the balanced molecular equation to get the balanced net ionic equation: \(Cr(OH)_{3}(s) + 3H^{+}(aq) + 3NO_{2}^{-}(aq) \rightarrow 3H_{2}O(l) + Cr^{3+}(aq) + 3NO_{2}^{-}(aq)\) (c):

Step 1: Identify reactants and predict products

The reactants are aqueous nitric acid (HNO₃) and aqueous ammonia (NH₃). The products will be water (H₂O) and a salt, which is ammonium nitrate (NH₄NO₃).

Step 2: Write the balanced molecular equation

Balance the equation by making sure the number of atoms of each element is equal on both sides: \(HNO_{3}(aq) + NH_{3}(aq) \rightarrow H_{2}O(l) + NH_{4}NO_{3}(aq) \)

Step 3: Write the balanced net ionic equation

Remove the spectator ions in the balanced molecular equation to get the balanced net ionic equation: \(H^{+}(aq) + NO_{3}^{-}(aq) + NH_{3}(aq) \rightarrow H_{2}O(l) + NH_{4}^{+}(aq) + NO_{3}^{-}(aq)\)